Prevention of ice formation



I ,Nov.22,1938. a. A. IQDRISCGLL 2,137,394"

PREVENTION pr ICE. FORMATION File d June 21, 1957 2 Sheets-Sheet 1[ohm/e0 ,4. omscou I INVENTOR Nov. 22, 1938 E. A. DRISCOLL I v 2,137,394

' PREVENTION OF ICE FORMATION Filed June 21, 1937 2 Sheets-Sheet 2EON/4R0 1. ole/scan INVENTOR BY MBW A RNEY STATES "PATENT. OFFICE 72,137,394 PREVENTION OF 1013: FORMATION Edward A. Driscoll, New York,\N. Y.. Application June 21, 1337, Serial No. 149,409

2 Claims.

The invention herein disclosed relates to the prevention of iceformation on aircraft surfaces. Special objects of the invention are toprovide practical and efficient means for preventing ice formation onaircraft supporting and control surfaces, which will' be readilyapplicable to existing equipment, which can be faired into or over thewing surfaces, control surfaces and the like, without materiallyaltering or impairing the aerodynamic efficiency of the same, which willbe reasonable in cost and sufficiently light in weight; durable andlasting in character and will require 2 only a reasonable amount ofavailable power.

Other objects of the inventionare to provide ice prevention apparatus ina form which may .be readily applied to and as readily removed, as 'itmay be considered necessary or unnecessary.

Other objects and the novel features of construction, combinations andrelations of parts .by which such objects are attained will appear inthe'course of the following specification.

The drawings accompanying and forming part of the specificationillustrate practical embodiments of the invention. These illustrationshowever are primarily by way of disclosure, since changes andmodifications in structure may be made a1l:within the true intent andbroad scope of the invention as hereinafter defined and claimed.

The drawings accompanying and forming part of the specificationillustrate practicalembodiments of the invention. These illustrationshowever are primarily by way of disclosure, since changes andmodifications in structure may be made all within the true intent andbroad scope of the. invention as hereinafter defined and claimed. 7

Fig. 1 is a perspective view of an airplane equipped with the invention.

Fig. 2 is a brokencross-sectional view of one of the wings showing howice formation preventers may be built into the leading edges of the wingand aileron structures.

Fig. 3 is an. enlarged broken sectional and perspective view of the iceformation prevention equipment as built into the leading edge of thewing. r

Fig. 4 is a broken sectional detail illustrating one methodof'manufacturing the equipment for ready attachment to and detachmentfrom the wings or other surfaces to be protected) The present Anventionutilizes the principle broadly covered in the Driscoll Patent 1,943,062of separating conductors of opposite polarity by absorbent medium, whichis an insulator when' dry and which when moist permits passage ofcurrent sufficient to prevent formation of ice. Special features relateto the structure and mounting of such equipment.

In Fig. 1, ice formation preventers are indicated at 5, applied to theleading edges and tips of the wings, at 6, on the leading edges of theailerons and at I, 8, 9, In H on the leading edges ofthe propellerhorizontal stabilizers, elevators, vertical stabilizer and rudderrespectively.

Each of such ice formationpreventers may be constructed substantially asindicated in Figs. 2 and 3 that is, with an underlying insulatingsupport,.-such as a layer of rubber I2, separated bus bars l3, l4,spaced conductors l5, [6, connected respectively with opposite bus bars,absorbent normally non-conductive intervening medium l1, and aprotective pervious covering I8. The latter may be a wire mesh screen,suitably secured at opposite edges as by screw fasteners |,-9, andsuitably faired into or to the supporting or control surfaces asindicated generally at 20.

To avoid electrolytic action and corrosive effects, the spacedconductors l5, l6, of opposite polarity may be thin strips, wires orstrands of lead or similar metal. l I

' The absorbent control medium l'l may be asbestos and may be infibrous, matted or woven condition. When dry, this material is anefflcient insulator and as it becomes moist, it permits flow of currentaccordingly.

The covering screen l8 forms a guard and protection over the absorbentnormal insulator, saving the asbestos from wear, reducing the airfriction of such material andat the same time, ad-

mitting moisture, the mesh of the screen and size of the wire beingselected to accomplish these several effects. Usually, these iceprevention devices are only needed about the leading edges of thesupporting-and control surfaces and hence it is sufficient to securethem as by rows of screw fastenings or equivalent along the oppositeedges of the same.

In Figs. 2 and 3, the protectors are shown set into the leading edges ofthe aircraft structure,' but it is contemplated that they may be simplyapplied over the leading edges as illustrated in Fig. 4 and be securedin a readily detachable fashion in such relation asby screw fasteningsIsa.

As in dry weather the deicing oriceformation prevention equipment isinoperative, it ispractical to connect the opposite bus-bars of all thedevices in a single circuit, such as indicated at 2|, leaving suchdevices then to automatically become eflecrings.

tive each in accordance with the extent to which it may becomemoistened. A currentlimiting device or devices such as an incandescentlamp or lamps may be cut into the circuit as indicated at 22. Currentmay be furnished by an air driven generator, storage battery or thelike. If ice preventers are used on the propeller, current may beconducted to the same through suitable slip The insulating support i2may be of rubber sufllciently flexible to conform to and take the shapeof the surface to which the device is applied and water-proof to preventabsorbed moisture soaking through to under portions before it can bedissipated by the heat resultant .from electrical conduction betweenopposed conductors. The ice preventers may be made up in the form offlexible pads of a size and shape to fit the particular surfaces forwhich they are intended and be connected direct with thetwo main feedwires in the manner generally indicated on dotted lines, Fig. 1. Ifextreme lightness is required, aluminum or similar conductors may beused, but as these conductors can be made as.

fairly thin light strips, it is practical to use a non-corrosive metalsuch as lead.

What is claimed is:

1. An ice preventer for aircraft, comprising a flexible pad conformableover the leading edge of an airfoil and composed of a flexible baselayer of water-proof material, an outside flexible layer pervious toatmospheric moisture, an intermediate layer of moisture absorbentmaterial electrically insulative when dry and electrically conductivewhen wet, said intermediate layer being flexible in nature and confinedand supported between said outer moisture pervious flexible layer andsaid inner flexible waterproof layer, electrically separated conductorsin said intermediate normally insulating but electrically conductivewhen wet moisture absorbent layer, means for connecting saidelectrically separated conductors in opposite sides of an electricalcircuit, said flexible outer and inner layers of said pad being securedtogether in tapering relation at opposite edges of the pad to enable theconforming of the flexible pad in stream-lined engagement about theleading edge of an airfoil.

2. In combination with an airfoil, a covering for preventing formationof ice thereon, comprising a base layer of non-absorbent water-proofmaterial, a layer of moisture absorbent material over said non-absorbentwater proof layer, said absorbent material being non-conductive toelectricity when dry and conductive to electricity when wet, electricalconductors separated by said absorbent material and insulated from eachother by said material when dry and electrically connected by saidmaterial .When wet, controllable means for supplying electric current tosaid conductors when formation of ice on said airfoil is imminent and astrong abrasion resistant covering over said absorbent layer, saidcovering possessing the mechanical strength necessary to fully confineand support said absorbent layer and being pervious to atmosphericmoisture to freely admit: atmospheric moisture throughout said absorbentlayer, said absorbent material being of a flocculent nature to readilyabsorb atmospheric moisture andv said pervious covering being secured tothe-airfoil under tension holding said absorbent material undercompression.

' EDWARD A. DRISCOLL.

